//===- llvm/CodeGen/TargetSchedule.h - Sched Machine Model ------*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file defines a wrapper around MCSchedModel that allows the interface to
// benefit from information currently only available in TargetInstrInfo.
// Ideally, the scheduling interface would be fully defined in the MC layer.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_CODEGEN_TARGETSCHEDULE_H
#define LLVM_CODEGEN_TARGETSCHEDULE_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/TargetSubtargetInfo.h"
#include "llvm/Config/llvm-config.h"
#include "llvm/MC/MCInstrItineraries.h"
#include "llvm/MC/MCSchedule.h"
namespace llvm {
class MachineInstr;
class TargetInstrInfo;
/// Provide an instruction scheduling machine model to CodeGen passes.
class TargetSchedModel {
// For efficiency, hold a copy of the statically defined MCSchedModel for this
// processor.
MCSchedModel SchedModel;
InstrItineraryData InstrItins;
const TargetSubtargetInfo *STI = nullptr;
const TargetInstrInfo *TII = nullptr;
SmallVector<unsigned, 16> ResourceFactors;
// Multiply to normalize microops to resource units.
unsigned MicroOpFactor = 0;
// Resource units per cycle. Latency normalization factor.
unsigned ResourceLCM = 0;
unsigned computeInstrLatency(const MCSchedClassDesc &SCDesc) const;
public:
TargetSchedModel() : SchedModel(MCSchedModel::GetDefaultSchedModel()) {}
/// Initialize the machine model for instruction scheduling.
///
/// The machine model API keeps a copy of the top-level MCSchedModel table
/// indices and may query TargetSubtargetInfo and TargetInstrInfo to resolve
/// dynamic properties.
void init(const TargetSubtargetInfo *TSInfo);
/// Return the MCSchedClassDesc for this instruction.
const MCSchedClassDesc *resolveSchedClass(const MachineInstr *MI) const;
/// TargetSubtargetInfo getter.
const TargetSubtargetInfo *getSubtargetInfo() const { return STI; }
/// TargetInstrInfo getter.
const TargetInstrInfo *getInstrInfo() const { return TII; }
/// Return true if this machine model includes an instruction-level
/// scheduling model.
///
/// This is more detailed than the course grain IssueWidth and default
/// latency properties, but separate from the per-cycle itinerary data.
bool hasInstrSchedModel() const;
const MCSchedModel *getMCSchedModel() const { return &SchedModel; }
/// Return true if this machine model includes cycle-to-cycle itinerary
/// data.
///
/// This models scheduling at each stage in the processor pipeline.
bool hasInstrItineraries() const;
const InstrItineraryData *getInstrItineraries() const {
if (hasInstrItineraries())
return &InstrItins;
return nullptr;
}
/// Return true if this machine model includes an instruction-level
/// scheduling model or cycle-to-cycle itinerary data.
bool hasInstrSchedModelOrItineraries() const {
return hasInstrSchedModel() || hasInstrItineraries();
}
/// Identify the processor corresponding to the current subtarget.
unsigned getProcessorID() const { return SchedModel.getProcessorID(); }
/// Maximum number of micro-ops that may be scheduled per cycle.
unsigned getIssueWidth() const { return SchedModel.IssueWidth; }
/// Return true if new group must begin.
bool mustBeginGroup(const MachineInstr *MI,
const MCSchedClassDesc *SC = nullptr) const;
/// Return true if current group must end.
bool mustEndGroup(const MachineInstr *MI,
const MCSchedClassDesc *SC = nullptr) const;
/// Return the number of issue slots required for this MI.
unsigned getNumMicroOps(const MachineInstr *MI,
const MCSchedClassDesc *SC = nullptr) const;
/// Get the number of kinds of resources for this target.
unsigned getNumProcResourceKinds() const {
return SchedModel.getNumProcResourceKinds();
}
/// Get a processor resource by ID for convenience.
const MCProcResourceDesc *getProcResource(unsigned PIdx) const {
return SchedModel.getProcResource(PIdx);
}
#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
const char *getResourceName(unsigned PIdx) const {
if (!PIdx)
return "MOps";
return SchedModel.getProcResource(PIdx)->Name;
}
#endif
using ProcResIter = const MCWriteProcResEntry *;
// Get an iterator into the processor resources consumed by this
// scheduling class.
ProcResIter getWriteProcResBegin(const MCSchedClassDesc *SC) const {
// The subtarget holds a single resource table for all processors.
return STI->getWriteProcResBegin(SC);
}
ProcResIter getWriteProcResEnd(const MCSchedClassDesc *SC) const {
return STI->getWriteProcResEnd(SC);
}
/// Multiply the number of units consumed for a resource by this factor
/// to normalize it relative to other resources.
unsigned getResourceFactor(unsigned ResIdx) const {
return ResourceFactors[ResIdx];
}
/// Multiply number of micro-ops by this factor to normalize it
/// relative to other resources.
unsigned getMicroOpFactor() const {
return MicroOpFactor;
}
/// Multiply cycle count by this factor to normalize it relative to
/// other resources. This is the number of resource units per cycle.
unsigned getLatencyFactor() const {
return ResourceLCM;
}
/// Number of micro-ops that may be buffered for OOO execution.
unsigned getMicroOpBufferSize() const { return SchedModel.MicroOpBufferSize; }
/// Number of resource units that may be buffered for OOO execution.
/// \return The buffer size in resource units or -1 for unlimited.
int getResourceBufferSize(unsigned PIdx) const {
return SchedModel.getProcResource(PIdx)->BufferSize;
}
/// Compute operand latency based on the available machine model.
///
/// Compute and return the latency of the given data dependent def and use
/// when the operand indices are already known. UseMI may be NULL for an
/// unknown user.
unsigned computeOperandLatency(const MachineInstr *DefMI, unsigned DefOperIdx,
const MachineInstr *UseMI, unsigned UseOperIdx)
const;
/// Compute the instruction latency based on the available machine
/// model.
///
/// Compute and return the expected latency of this instruction independent of
/// a particular use. computeOperandLatency is the preferred API, but this is
/// occasionally useful to help estimate instruction cost.
///
/// If UseDefaultDefLatency is false and no new machine sched model is
/// present this method falls back to TII->getInstrLatency with an empty
/// instruction itinerary (this is so we preserve the previous behavior of the
/// if converter after moving it to TargetSchedModel).
unsigned computeInstrLatency(const MachineInstr *MI,
bool UseDefaultDefLatency = true) const;
unsigned computeInstrLatency(const MCInst &Inst) const;
unsigned computeInstrLatency(unsigned Opcode) const;
/// Output dependency latency of a pair of defs of the same register.
///
/// This is typically one cycle.
unsigned computeOutputLatency(const MachineInstr *DefMI, unsigned DefOperIdx,
const MachineInstr *DepMI) const;
/// Compute the reciprocal throughput of the given instruction.
double computeReciprocalThroughput(const MachineInstr *MI) const;
double computeReciprocalThroughput(const MCInst &MI) const;
double computeReciprocalThroughput(unsigned Opcode) const;
};
} // end namespace llvm
#endif // LLVM_CODEGEN_TARGETSCHEDULE_H